Electrical isolation of bi-directional data streams is particularly desirable in communication systems utilizing single wire links. However, bi-directional isolation circuits used in the past have faced problems with latching. A latching condition may occur when, for example, under conditions in which a receive logic path goes low and transfers this input low to its output, the output in turn is detected as being low, and this low signal is returned to the input, resulting in the original input being pulled/latched low. This undesirable latched condition remains even when the external low drive signal is removed.
Chargers, such as those used for charging the batteries of portable radios, often utilize bi-directional circuits for electrical isolation of data streams and can therefore encounter the latching issues discussed above. In a multi-unit charger for example, noise coupling from one charger pocket to another may lead to a latched condition. Likewise, when a computer is coupled to a multi-unit charger, such as for data retrieval or programming, ground loops may lead to a latched condition. The latched condition at the charger can lead to improper charging and/or false status indications to the user.
Accordingly, there is a need for an improved bi-directional circuit. Such a circuit would be beneficial to various electronic devices, such as battery chargers.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.